Adjustable wrenches

ABSTRACT

An open end wrench and a socket wrench are described which are selectively adjustable to rotate fasterners dimensioned pursuant to the English system or the metric system. Both wrenches compris first and second elements having parallel surfaces spaced apart to engage flats, of a given width, on a fastener. Parallel linkage means control relative moventment of the two elements between first and second positions. In the first position, the linkage is parallel to the flat engaging surfaces and the flat engaging surfaces thereof are spaced for rotation of a fastener having flats of the given width. In the second relative position of the elements, the linkage means is generally normal to the flat engaging surfaces and the flat engaging surfaces thereof are offset, with one surface of the first element being laterally spaced from one surface of the second element a predetermined lesser distance for rotation thereby of a fastener having flats of a width approximately said lesser distance.

The present invention relates to wrenches and more particularly toimprovements in adjustable wrenches.

Wrenches are a well known class of tools for rotating or applying torqueto rotatable members, primarily threaded fasteners, such as nuts, boltsand screws. Rotation is effected through flats on opposite sides of theaxis of the fastener. (While wrenches may be employed in the rotation ofany rotatable member, for the sake of simplicity, reference herein willbe made to fasteners.)

In the class of fasteners of interest the fasteners have square orhexagonal cross sections, thus providing two or three pairs of flatswhich may be engaged by the wrench in effecting rotation. The widthacross such flats defines the size of wrench required.

There are two primary types of wrenches used in rotating fastenershaving these cross sections, namely open end wrenches and socketwrenches, box wrenches being considered a variation of the socketwrench. These wrenches are available in sets to span various ranges offastener sizes, or, more particularly, the range of widths across flats.

Until recently, in the United States, practically all threaded fastenerswere dimensioned in inches, pursuant to the English system. Thus, onecommon range of wrench sizes is 1/4 inch to 1 inches, with wrenchesbeing provided for each even sixteenth increment of an inch. Anexperienced worker can visually identify the size of a nut or bolt andautomatically select the appropriate size wrench. This ability greatlyfacilitates repair work, where the use of different size fasteners is tobe expected. resulting from domestic manufacture, there is an increasinguse of fasteners dimensioned pursuant to the metric system. In thereferenced range of 1/4 inch to 1 inch, the width across fastener flatsis, generally, in even millimeters in one or two millimeter increments.These fasteners are, of course, intended to be rotated by wrenches sizedin accordance with the metric system.

The difference between the standard English sizes, i.e., even sixteensand the nearest even millimeter size, is sufficient that the Englishsystem wrenches are not, for the most part, effective in rotating metricfasteners, particularly where a significant amount of torque isrequired.

To deal with the two measurement systems, it has become a commonpractice to have at hand two separate sets of wrenches, which has anobvious cost disadvantage.

More importantly, repair work, for example, becomes more time consuming.While visually identifying sixteenth inch increments can be readilydone, it is extremely difficult to distinguish between metric andEnglish sized fastener sizes. Thus the facility of automatic wrenchselection is no longer available and wrench selection becomes a trialand error process.

Obviously the use of wrenches having adjustable gripping surfaces wouldobviate the need of two sets of wrenches. However, in most of the manyproposals for adjustable wrenches, more time would be lost in effectingthe necessary adjustment than would be required in selecting the properwrench from two sets.

A further shortcoming of the many prior art, adjustable wrenches, is alack of rigidity in accurately spacing the surfaces which engage theflats of the fastener. This makes them ineffective in rotating afastener, where a significant torque force is required.

Accordingly, the object of the present invention is to facilitate therotation of fasteners manufactured pursuant to either the English ormetric system.

Another object of the present invention is to provide an adjustablewrench, suitable for such purposes, which may be readily switchedbetween English and metric system positions.

A further object of the invention is to provide an adjustable wrenchwhich has a strength and rigidity approaching that of a single size,integral wrench.

Yet another object of the invention is to provided both open end socketwrenches suitable for the above ends.

These ends may be attained by a wrench for rotating a fastener havingtorquing flats. The wrench has the capability of gripping flats having afirst width or a second, lesser width.

The wrench has first and second elements. Each element has a pair ofopposed, parallel engaging surfaces spaced a distance approximating thefirst flat width.

A parallel linkage controls relative movement of the first and secondelements between first and second relative positions.

In the first position, the parallel linkage is generally parallel withthe parallel engaging surfaces and the engaging surfaces of the firstelement are aligned with the engaging surfaces of the second element.

In the second position, the parallel linkage is generally normal to theengaging surfaces and the engaging surfaces of the upper element areparallel to and offset from the engaging surfaces of the lower element.The fastener flats of said lesser width may be engaged by one surface ofthe upper element and one oppositely facing surface of the lower elementin rotating the fastener.

Preferably the parallel linkage mechanism comprises a plurality of pins.Each pin has upper and lower portions offset on parallel axes. The upperportions of the pins are pivotally mounted in the first element and thelower portions are pivotally mounted in the second element.

The first and second elements may be of a C-shaped configuration toprovide an open end wrench. A handle extends outwardly from the closedend of one of these elements to enable manual application of torque inrotating a fastener.

Alternatively, the second element may have a hexagonal recess defined bythe flat engaging surfaces thereof, plus two additional pairs of flatengaging surfaces. The first element may have a central passagewaydefined in part by the flat engaging surfaces thereof. The first elementpassageway may also be defined bya third surface which is parallel withthe surfaces of one of the other pairs of surfaces on the secondelement. This third surface, in the second relative position of theelements, is laterally spaced from one of the surfaces with which it isparallel, a distance also approximating said lesser flat width, whenadjusted for rotation of a smaller fastener.

The above and other related objects and features of the invention willbe apparent from a reading of the following description of preferredembodiments of the invention, with reference to the accompanyingdrawings, and the novelty thereof pointed out in the appended claims.

In the drawings:

FIG. 1 is an exploded, perspective view of an open end wrench embodyingthe present invention;

FIG. 2 is a plan view of the present open end wrench;

FIG. 3 is a section taken at the interface between adjustable elementsof the wrench;

FIG. 4 is a plan view of the same wrench, adjusted for rotation of afastener having flats of a lesser width;

FIG. 5 is a section taken on line 5--5 in FIG. 4;

FIG. 6 is a plan view, partly in section, of one of the pins controllingadjustment of the wrench;

FIG. 7 is a plan view of a socket wrench embodying the presentinvention;

FIG. 8 is a section taken on line 8--8 in FIG. 7; and

FIG. 9 is a section taken on line 9--9 in FIG. 7, with the socketadjusted for rotation of a fastener having flats of a lesser width.

Wrenches, as noted above, are a basic tool for the rotation of threadedfasteners, They take several forms. Attention herein is first directedto open end wrenches. Rotation of a a large class of fasteners iseffected through opposite surfaces of a square or hexagonal crosssection. Both nuts and the heads of screws and bolts are provided withsuch cross sections for torqueing purposes. Opposite sides of the crosssections provide parallel flats which are engaged by a wrench inrotating the fastener. The width of the flats, i.e., the distancetherebetween needs to be approximated by the distance between thesurfaces of the wrench which engage them in rotating the fastener.

An open end wrench embodying the present invention is illustratd inFIGS. 1-6. It comprises an upper C-shaped element 10 and a lowerC-shaped element 12. A handle 14 is formed integrally with and extendsfrom the closed end of the C-shaped element 12.

The C-shaped element 10 has opposed, parallel surfaces 16, 18 and theC-shaped element 12 has opposed, parallel surfaces 16', 18', Thedistance between the surfaces 16, 18 and the distance between thesurfaces 16', 18' approximates and is slightly larger than an evensixteenth of an inch. For illustrative purposes, the nominal distancecould be set at 9/16 inch.

The C-shaped elements, 10 and 12, are interconnected by three pins 20which control relative movement therebetween. Each pin 20 comprises anupper portion 22 and a lower portion 24. The upper and lower portionsare formed cylindrically about offset axes a and b. The upper portions22 are pivotally in the upper element 10 and the lower pin portions arepivotally mounted in the lower C-shaped element 12. The elements 10 and12 may be provided with matching projections 26 and grooves 28 in theirmating surfaces.

It will be appreciated that the upper and lower portions of the pins 20may be integrally formed by reason of the fact that the offset betweenthe axes a and b is substantially less than their diameters. Forpurposes of structural strength it is preferred that the offset be nomore than about 30% of the diameters of the upper and lower portions.The offset is exaggerated in the drawings.

In assembling the exploded relationship of the components illustrated inFIG. 1, the upper and lower pin portions 22, 24 have lengths greaterthan the thickness of the C-shaped elements 10, 12 and project beyondthe outer surfaces thereof. These projecting portions may then be swagedto form the heads (FIG. 5) which hold the components in assembledrelation.

The elements 10 and 12, in combination with the pins 20 form a parallellinkage. The portion of the pin material between the axes a and bfunctions as a link. This is further illustrated in FIG. 6 by the brokenline showing of link L which represents the linkage function of the pin20. The smaller, broken circles make more apparent the pivotalconnections for the link function of the pins 20 and how they form aparallel linkage mechanism in combination with the elements 10, 12.

FIGS. 2 and 3 illustrate the wrench adjusted for the English measurementsystem, for use with fasteners having, as indicated above, a widthacross its flats of 9/16. In this relative position of the elements 10and 12, the parallel linkage is generally parallel to the flat engagingsurfaces 16, 18, 16', 18'. The engaging surfaces of the upper element 10are aligned with the engaging surfaces of the lower element 12.

FIGS. 4 and 5 illustrate the wrench elements 10 and 12 in their secondrelative position. The selected nominal size of 9/16 inch illustratesthat certain English system sizes sufficiently approximate an evenmillimeter size to permit their use on metric fasteners. Expresseddecimally, 9/16 inch is 0.5625 inch and 14 millimeters is 0.5512 inch.The difference is only 0.0113 inches. A nominal clearance of 0.0113between the gripping surfaces is within permissible limits for use ofthe 9/16 spacing on fasteners having a width across flats of 14millimeters.

The wrench as seen in FIGS. 4 and 5 is adjusted for a flat width of 13millimeters 0.5118 inch). The offset between the axes a and b, and theeffective length of the links L is 0.0507 inch. Thus, in the secondposition, the linkage is generally normal to the engaging surface 16, 18which are maintained parallel with the gripping surfaces 16', 18' andoffset therefrom. In this second position, the surface 16 of the upperelement 10 and the surface 18' of the lower element 12 are spaced apart13 millimeters and become the active engaging surfaces for rotating ametric sized fastener, FIG. 5.

Reference is next made to FIGS. 7-9 for a description of a socket wrenchembodying the present invention. This type wrench is conventionallyprovided as a set of "sockets" having recess sized, in accordance withthe English system for engagement with fasteners having flat widths ineven sixteenth inch increments. The sockets are telescoped over a nut orbolt head for engagement of the walls of the recess with the flats, orcorners of the flats, to rotate the fastener. It is more common toemploy socket wrenches in the rotation of fasteners having hexagonallydisposed flats. Accordingly, the recesses of the sockets are usuallyprovided with a hexagonal outline, or a so called twelve point outline.

A socket 40 comprises an upper element 42 and a lower element 44. Thelower element 44 is provided with a square opening 46 for detachablyreceiving a torque bar 48, in conventional fashion.

The lower element 44 is provided with a recess of hexagonal outline forengagement with a hexagonal nut or bolt head having a corresponding flatwidth. The recess is defined by walls designated 50a, 50b, 50c, 50d, 50eand 50f. This provides three pairs of parallel engaging surfaces, eachspaced apart the same, even nominal sixteenth of inch incrementaldistance. Again this may be exemplified by a 9/16 inch size.

As with the first embodiment, the upper element 42 is manually shiftablebetween a first, English system position and a second metric systemposition. This movement is controlled by three pins 52 which provide aparallel linkage mechanism which 25 operates, in principle, in the samefashion as described in connection with the open end wrench. Thus, eachpin comprises an upper portion 54 formed cylindrically about an axiswhich is offset from the parallel axis about which a lower cylindricalportion 56 is formed.

The lower ends of the cylindrical portions 56 are threaded to receivenuts 58. The upper portions 54 are rotatable received in the upperelement 42. A detachable retaining ring 60 is received in a groove 62formed in the element 42 and engages grooves 64 in the upper pinportions 54, to hold the elements and pins in assembled relation.

The upper element 42 has a pair of parallel, opposed engaging surfaces66a and 66d and a second pair of opposed surfaces 66c, 66f which arespaced apart the exemplary, nominal 9/16 inch distance. In the Englishmeasurement system adjustment (illustrated in solid lines in FIG. 7),the surfaces 66a and 66d are aligned, respectively, with the lowerelement surfaces 50a, 50d.

The central passageway is also defined by opposed surfaces 66b, 66e. Inthe English system adjustment, the surface 66b may be aligned with thelower element surface 50b, with the surface 66e spaced outwardly fromthe surface 50e.

In the first relative position of the elements 42, 44, FIG. 7 (theEnglish system setting), the parallel linkage comprising the pins 52 isdisposed parallel to the surfaces 50a, 66a, a, as well as the pairedsurfaces 50d, 66d.

The elements 42, 44 are manually shiftable to the second relativeposition illustrated by the phantom position of FIG. 7 and in FIG. 9. Inthis position the parallel linkage is generally normal to the primaryflat engaging surfaces 66a of the upper element 42 and 50d of the lowerelement 44. These surfaces become the primary flat engaging surfaces forrotation of a fastener. The offset between the axes of the upper andlower pin portions, 54, 56, is selected so that the distance betweenthese surfaces is, nominally an even millimeter dimension (again 13millimeter, for illustrative purposes) and suitable for rotation of ametric fastener.

It will also be seen in FIG. 7, that the surfaces 66e and 50b are spacedthe same, even millimeter distance and may provide an additional pair offlat engaging surfaces for rotation of metric fasteners. The initialoffset of the surface 66e, from the surface 50e is selected so thatthese surfaces will be aligned when the upper element is displaced toits metric system position.

While there are a lesser number of flat engaging surfaces effective inrotating the smaller, metric fastener, nonetheless, they are adequateand suitable for most all situations.

In the described embodiments, the English system positions provideessentially the same flat engaging forces as in conventional wrenches.There is some compromise in the metric system. This choice has been madein view of the expectation that metric fasteners will be less frequentlyencountered. If the situation should be otherwise, then the so-called"first" positions could be sized for metric fasteners and the "second"positions could be sized for English measurement system fasteners.

Other variations will occur to those skilled in the art within thespirit and scope of the present inventive concepts which are set forthin the following claims.

Having thus described the invention, what is claimed as novel anddesired to be secured by Letters Patent of the United States is:
 1. Awrench for engaging flats on a fastener to effect its rotation, saidwrench being adjustable to selectively rotate fasteners with flatshaving a given width or flats having a given, lesser width, said wrenchcomprisinga first element having parallel, opposed flat engagingsurfaces spaced apart a distance approximating said given flat width, asecond element having parallel, opposed flat engaging surfaces spacedapart a distance approximating said given flat width, and parallellinkage means controlling relative movement of said elements betweenfirst and second positions, said elements, in their first position,having their first engaging surfaces aligned by the parallel linkagebeing parallel to said flat engaging surfaces, said elements, in theirsecond position, having their flat engaging surfaces offset, with thelinks of the parallel linkage being generally normal thereto, wherebyone flat engaging surface of the upper element and an oppositely facingengaging surface of the lower element are laterally spaced a distanceapproximating said lesser flat width.
 2. A wrench as in claim 1,whereinthe parallel linkage means comprise a plurality of pins, each pinhaving an upper portion pivotally mounted in the first element and alower portion pivotally mounted in the second element about an axislaterally offset from the axis of the upper portion, the lateraldistance between said axes approximating the difference between saidgiven width and said lesser given width.
 3. A wrench as in claim 2,whereinthe first and second elements are C-shaped and the flat engagingsurfaces thereof extend inwardly from the open end of the C-shapedconfigurations, and the pivotal axes of two pins are disposedintermediate the lengths of the flat engaging surfaces and arerespectively disposed on opposite sides thereof, and further wherein ahandle extends outwardly from the closed end of one of said C-shapedelements.
 4. A wrench as in claim 3 whereinthe spacing between the flatengaging surfaces of the upper and lower elements is, nominally, an evensixteenth inch fraction in the range of 1/4 inch to 1 inch, and thedistance between the offset, pivotal axes of each pin approximates thedifference between the even fractional inch spacing of the flat engagingsurfaces and a smaller, even millimeter dimension.
 5. A wrench as inclaim 2 whereinthe second element has a central recess of hexagonaloutline defined by the spaced, flat engaging surfaces thereof, and twoadditional pairs of equally spaced, parallel flat engaging surfaces,said second element further having means for detachably receiving atorque bar.
 6. A wrench as in claim 5 whereinthe first and secondelements have a generally circular cross section, and the first elementhas a central recess of hexagonal outline defined in part by the flatengaging flats thereof and two additional pairs of flat engagingsurfaces, the flat engaging surfaces of one of said additional pair ofsurfaces being respectively aligned with the flat engaging surfaces ofone of the additional pair of surfaces of the second member, in thefirst position of the elements, the other additional surfaces of thesecond element in the first position of the elements and having itsother surface spaced from said one surface of the other additional pairof surfaces of the second element, a distance approximating said lesserflat width in the second position of the elements.